Solvent refining of hydrocarbon oil



Patented Sept. 11, 1934 tenses 1 c n w s is o soLviiN'r REFINING or HYnRooAaBoN I No Drawing. Applicatibn October 26, I933,

Serial No. 695,323

3 Claims. (Cl. 196-13) This invention relates to refining hydrocarbon oil, and more particularly to refining mineral oil by solvent extraction.

The invention contemplates the treatment and refining of mineral oil with a selective solvent whereby the oil is separated into fractions having desired characteristics.

The invention has particular reference to the extractive treatment of mineral oil with furm furaldoxime, a cyclic organic compound which is an aldoxime of furfuraldehyde.

I have found that furfuraldoxime possesses selective solvent action as between various constituents of oil and, therefore, is suitable for 5 extracting certain constituents from the oil for the production of products of desired characteristics. This solvent exerts a preferential solvent action on the relatively non-parafiinic constituents of mineral oil, including aromatic, naphthenic, and unsaturated bodies. Moreover, it exerts a solvent action upon certain sulphur compounds of the oil.

The solvent of my invention is, therefore,

adapted for separating oil into fractions respectively rich in relatively parafiinic and relatively non-parafi'inic constituents. It is of particular advantage, for example, in treating straight-run or cracked naphtha for the separation therefrom of fractions which are rich in aromatic or other constituents having a relatively high anti-knock value. It is also suitable for the extractive treatment of lubricating oil for the purpose of separating the oil into fractions of differing viscosity index.

In the application of my invention to the treatment of petroleum naphtha for the separation therefrom of a fraction having high antiknock properties and, therefore, suitable as a superior motor fuel, one part of naphtha is mixed and agitated with about two parts of the solvent liquid. The mixture is maintained at a temperature of around 200 F. or higher, and allowed to separate into two fractions or layers. One layer comprises the relatively paraiiinic portion of the naphtha, substantially insoluble in the solvent liquid, while the other layer comprises the relatively less paraffinic or aromatic portion of the naphtha dissolved in the bulk of the solvent liquid. These layers are separated and the solvent liquid removed therefrom, thereby producing a naphtha fraction of highly paraffinic character but of relatively low anti-knock value, and another fraction rich in aromatics and of relatively high anti-knock value.

For example, when extracting a cracked naphtha distillate, having an octane value of around 74, in the foregoing manner, the undissolved fraction, comprising about 'Zi)% of the original naphtha, had an octane value of 64;, while the dissolved fraction, comprising about so 39% of the original naphtha, had an octane value of around 90.

Since furfuraldoxime possesses a relatively high boiling point, namely, 401 F., vhich is somewhat higher than the boiling range of motor 5 fuel, dissolved naphtha of motor fuel boiling range may be readily separated from the solvent by ordinary vaporization or fractional distillation, without exposing the naphtha to undue heating. 7a..

The fractions into which the naphtha is separated, as above described, may be subjected to treatment with additional quantities of the solvent for the purpose of obtaining a series of fractions of differing characteristics. The conditions 7 of temperature and ratio of solvent to naphtha may be varied for the purpose of effecting the particular degree of extraction desired. The temperatures employed may range from around 200 F. to 250 or 300 F., or even higher if de- 30. sired. The extent to which lower temperatures of extraction may be employed is limited to those at which the solvent, when mixed with. the oil, remains in a liquid condition, since furfuraldoxime has a melting point of around 5.

Pressure may be employed in order to prevent vaporization, either of the oil undergoing treatment or or the solvent during the treatment except, of course, where it may be desired to extract the oil in the vapor phase, and in which case the .0. pressure may be adjusted accordingly.

It is contemplated that the treatment maybe carried out either in batch or by continuous counter-current methods.

The invention is not necessarily limited to the 5 treatment of straight-run or cracked naphtha, but it may also be applied to the refining and purification of various hydrocarbon or mineral oil fractions, including lubricating oil and kerosene, etc., as well as residual or distillate fracm tions, or products derived from petroleum or other sources. Accordingly, it may be applied to the extraction of lubricating oil stock for the purpose of separating it into fractions differing from each other with respect to their lubricating char- 1 0 5 acteristios.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations llo should be imposed as are indicated in the appended claims.

I claim:

1. The method of treating hydrocarbon oil containing relatively paraffinic and relatively nonparaifinic constituents including naphthenic, aromatic, and unsaturated bodies, with a solvent having selective solvent action as between said paraifinic and non-paraffinic constituents, comprising extracting the oil with furfuraldoxime whereby the oil is separated into fractions respectively rich in the relatively paraffinic and relatively non-paraffinic constituents.

2. The method of treating hydrocarbon oil containing relatively paraffinic and relatively nonparaflinic constituents including naphthenic, aro- 

